1. Field of the Invention
The present invention relates to a system and method for automatically controlling a vehicle speed to a desired cruise speed using a microcomputer in which a power supply to an actuator for actuating an engine driving torque adjusting mechanism is enabled only when all of a plurality of factors of determining whether a cruise control can be carried out satisfy a condition to enable the cruise speed control to execute.
2. Background of the Art
A Japanese Patent Application First Publication No. Sho 60-42131 published on Mar. 6, 1985 exemplifies one of previously proposed systems for automatically controlling a vehicle speed to a desired cruise speed applied to automotive vehicles.
In the previously proposed automatic cruise speed controlling system, an actuator for actuating an engine throttle valve so as to adjust an opening angle thereof is controlled by means of a control unit in accordance with a command issued from a command generating unit (having a plurality of switches through an operation of one of the switches) so that a current speed coincides with a set cruise speed at which the vehicle is desired to cruise.
As recent trends, the control unit includes a microcomputer to meet the demand of small-sized, high performance control unit.
In addition, in such a previously proposed automatic cruise speed controlling system as described above, when a brake pedal is depressed or clutch pedal is depressed and an operation signal indicating that the brake or clutch pedal is operated is produced during the cruise run controlled by the system, the power supply to the throttle actuator is inhibited in response to the operation signal. Thus, the cruise control operation using the control unit is released. At this time, the vehicle speed can be decreased unless the driver depresses an accelerator pedal. Furthermore, when the brake pedal is released or the clutch pedal is released and one command from the command generating unit is issued to the control unit, the power supply to the actuator is resumed to carry out the cruise operation in accordance with the command issued from the command generating unit.